Valve Overlap

[Bruce Plecan]

-----Original Message-----
From: Robert Harris <bob at bobthecomputerguy.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Thursday, March 25, 1999 11:03 AM
Subject: Re: Valve Overlap


<Snip>
>Now if you want to spin the turbo up in a hurry, you might consider
selective
>spark RETARD.  Buick GN's do it all the time.

Can I ask where in the program this is incorporated?.
>
>By momentarily retarding the spark, say to 30 degrees after TDC, combustion
>starts way late and slow and the majority of the charge burns and expands
in
>the exhaust manifold greatly increasing the volume of gas to spin the turbo
>which greatly increases the inlet charge .....

Wouldn't that be kinda hard on the exhaust valve?.
Bruce

>The result is very quick acceleration by exactly the effect that you want -
>blowing fire into the exhaust - without being defeated by the physics.  And
>its on list topic.